1. Field of the Invention
This invention is related to an apparatus for deveining shrimp, and, more specifically, to an apparatus for cutting the sand vein from shrimp with improved sanitation.
2. Description of Related Art
FIG. 1 is a frontal, right-side perspective view of a shrimp cutting machine from U.S. Pat. No. 2,702,921 to Pinney. In Pinney, a shrimp is fed manually into the machine 1 which holds the shrimp in a stretched out position while it is being cut lengthwise down the center of the back and subsequently cut a second time on each side of the center cut. Shown on the top of the top cover 4 are a pair of guide fingers 11 and 12 between which shrimp are placed with their back sides up, and are then pushed head-first until they come in contact with a pair of flexible rubber disks 8 and 9.
FIG. 2 is a frontal, right-side perspective view of the guide fingers 11 and 12 and the flexible rubber disks 8 and 9. The flexible rubber disks 8 and 9 rotate around an axle 10 and grasp the shrimp, pulling it into the machine.
FIG. 3 is a left side view of the interior mechanisms of the shrimp cutting machine 1. The flexible disks 8 and 9, upon pulling the shrimp into the machine, hold the shrimp against the surface of a feed drum 6. The feed drum 6 is rotated at high speed by an electric motor 5 and a drive belt 7. A chain 20 and sprockets drive the flexible disks 8 and 9, a single central cutting disk 15, and a pair of cutting disks 17 and 18.
FIG. 4 is a front view of the interior mechanisms of the shrimp cutting machine 1, showing more definitively the positioning of the flexible disks 8 and 9, the single cutting disk 15, and the pair of cutting disks 17 and 18.
In operation, each shrimp is individually fed into the machine by hand, head first, between the guide fingers 11 and 12. As the shrimp engages the flexible rubber disks 8 and 9, which are revolving at a high rate of speed, the shrimp is drawn downwardly around the periphery of the feed drum 6. The bottom of the shrimp is pressed against the feed drum 6, thus supporting the shrimp on the bottom and also holding each shrimp in proper position so that the cutting disk 15 can cut the shrimp longitudinally down the center of the back.
The shrimp continues to follow the periphery of the feed drum 6 and is carried past the revolving pair of cutting disks 17 and 18 which cut the shell structure on each side of the center cut previously made by the single cutting disk 15. The shrimp is then ejected from the bottom of the machine 1. The sand vein found in the back of the shrimp is cut by the single cutting disk 15, and when the second pair of disks 17 and 18 come into action, the sand vein is automatically discharged from the body of the shrimp.
As is readily apparant from FIGS. 3 and 4, the machine disclosed in U.S. Pat. No. 2,702,921 is quite complex, and this complexity makes it susceptible to mechanical breakdown. In addition, the placement of the electric motor 5 and the chain and sprocket drive mechanism used to drive the drum 6, flexible disks 8 and 9, and cutting disks 15, 17 and 18 makes this machine extremely difficult, if not impossible, to keep in a clean and sanitary condition. As the shrimp is cut, the sand vein is stripped away, and flying debris and bodily fluids from the shrimp cover the inner workings of the machine. It must be frequently disassembled, cleaned and sanitized to keep the machine in sanitary working condition.
An improvement to the machine disclosed in U.S. Pat. No. 2,702,921 was made when it was discovered that the secondary cuts performed by the pair of cutting disks 17 and 18 were unnecessary in the process of deveining and deshelling the shrimp. A redesign of the machine was undertaken, with the secondary blades removed for simplification. Additionally, it was attempted to isolate the electric motor and drive mechanism from the flying shrimp debris resulting from the cutting process. The motor and drive mechanism was placed inside a housing while a pair of flexible rubber disks and a cutting disk were mounted outside the housing and covered with a protective shield.
FIG. 5 is a frontal, left-side perspective view of a prior art shrimp deveining apparatus with an external cutting mechanism covered by shield 55, and an internal motor and drive mechanism within a housing 44 (shown in phantom). An electric motor 31 turns a drive belt 32 which in turn drives two parallel shafts, an upper shaft 33 and a lower shaft 34. The shafts extend through openings in a circular housing plate 35.
FIG. 6 is a frontal, right-side perspective view of the prior art shrimp deveining apparatus of FIG. 5, with the protective shield 55 removed. It can be seen that a pair of flexible rubber disks 36 and 37, similar to flexible disks 8 and 9 in FIGS. 1-4, are mounted near the end of the upper shaft 33. A single cutting disk 38 is mounted near the end of the lower shaft 34. An adjusting shaft 39 extends through a slot 41 in the circular housing plate 35 and has a rubber idler roller 42 mounted near its outside end. The idler roller 42 freewheels on the adjusting shaft 39, and is held in position by a rubber disk 43 on each side.
During operation, the flexible rubber disks 36 and 37, the cutting disk 38, and the adjusting shaft 39 and idler roller 42 are covered with the protective shield 55. The shield 55 slidably mounts on the circular housing plate 35. Shrimp are placed through a small opening 56 in the top of the shield 55, and exit through a large opening 57 in the bottom of the shield 55.
Referring again to FIG. 5, the inside end of the adjusting shaft 39, i.e., the end which is inside housing 44, is mounted with a set screw 45 to an L-shaped arm 46 which is mounted at a pivot point 47 on the frame 48 of the housing 44 above the upper shaft 33. One end of an adjusting rod 49 is mounted at the other end of the L-shaped arm 46. The adjusting rod 49 extends diagonally through the housing 44 and exits through a flexible mount 50 extending through an opening in the front side 51 of the housing 44. The external end 52 of the adjusting rod 49 is threaded, and an adjusting knob 53 is mounted thereon. By rotating the adjusting knob 53, the adjusting rod 49 may be extended or retracted from the housing 44, thereby rotating the L-shaped arm 46 about its pivot point 47. This rotation causes an arcuate change of position of the adjusting shaft 39 as it extends through the slot 41 in the circular housing plate 35. This causes the adjusting shaft 39 and the idler roller 42 mounted thereon to move closer to or, if rotated the opposite direction, farther away from the cutting disk 38.
Although this machine is a significant improvement over the original design disclosed in U.S. Pat. No. 2,702,921, it still has a serious sanitation problem. A considerable amount of fluid, shrimp veins, and pieces of shrimp shell are disbursed within the shield 55 during operation of the machine. The slot 41 in the circular housing plate 35, through which the adjusting shaft 39 extends, allows a significant portion of this material to pass through the circular housing plate 35 and into the motor housing 44. This creates unsanitary conditions which are unsatisfactory from a health standpoint. It has been attempted to block the entry of debris into the housing 44 by placing a rubber disk (not shown) over the adjusting shaft 39 adjacent to the circular end plate 35. However, this technique has not been successful in totally eliminating the entry of debris into the housing 44.
Additionally, the flexible disks 36 and 37 have previously been made of rubber. However, the surfaces of disks made of rubber are porous, and are susceptible to growths of microscopic bacteria. Rubber disks, therefore, will not be approved for commercial food-preparation activities by governmental inspection agencies.
A shrimp deveining machine is needed which rapidly and efficiently deveins shrimp while maintaining government-approved sanitary conditions. This requires completely preventing the entry into the motor housing of any of the debris from the cutting and deveining process, and the incorporation of new flexible disks made of elastomeric material with acceptably low porosity. It is an object of the present invention to provide such a shrimp deveining machine.